The Core type-matcher should look through PredTypes

[ghc-hetmet.git] / compiler / types / Unify.lhs

diff --git a/compiler/types/Unify.lhs b/compiler/types/Unify.lhs
index 8ffee89..b99d387 100644 (file)
--- a/compiler/types/Unify.lhs
+++ b/compiler/types/Unify.lhs
@@ -146,11 +146,12 @@ match :: MatchEnv -- For the most part this is pushed downwards
                        --      in-scope set of the RnEnv2
       -> Type -> Type  -- Template and target respectively
       -> Maybe TvSubstEnv
--- This matcher works on source types; that is, 
--- it respects NewTypes and PredType
+-- This matcher works on core types; that is, it ignores PredTypes
+-- Watch out if newtypes become transparent agin!
+--     this matcher must respect newtypes
 
-match menv subst ty1 ty2 | Just ty1' <- tcView ty1 = match menv subst ty1' ty2
-                        | Just ty2' <- tcView ty2 = match menv subst ty1 ty2'
+match menv subst ty1 ty2 | Just ty1' <- coreView ty1 = match menv subst ty1' ty2
+                        | Just ty2' <- coreView ty2 = match menv subst ty1 ty2'
 
 match menv subst (TyVarTy tv1) ty2
   | tv1' `elemVarSet` me_tmpls menv